Discharge lamp control system with an electromagnetic lock for the simmering shutter



g- 26, 1952 A. H. WILLOUGHBY 2,603,640

DISCHARGE LAMP CONTROL SYSTEM WITH AN ELECTROMAGNETIC LOCK FOR THE SIMMERING SHUTTER Filed May 2, 1949 2 SHEETS-SHEET 1 ii H 4 zzz zzzaws Invewbor Ani'horv H. \MLLo Aug. 26, 1952 A. H. WILLOUGHBY 2,608,640

- DISCHARGE LAMP CONTROL SYSTEM WITH AN ELECTROMAGNETIC LOCK FOR THESIMMERING SHUTTER Filed May 2, 1949 2 sHEETs-sHEET 2 lnven-lrbr'z An'thong H. \MLLoLgbd.

the lever in the position 8, as shown in Figs. 1 and 3, thus preventing it from being moved into the position 8 to open the shutters and 6, until the coil [4 is energized by means of a relay operated by the voltage across the lamp, as will be described later. When the said voltage attains the required minimum value, current flows through the coil I4 and the soft iron bar I3 is then attracted towards the coil and moves up- Wards into the position [3 indicated by broken lines in Fig. 3, thus releasing the lever 8 which is then free to move, in a direction indicated by the arrow B (Fig. 3), at right angles to the direction of movement of the bar [3, from the position 8' to the position 8, thus opening the shutters 5 and 6.

In Fig. 2, which shows diagrammatically the circuit arrangements associated with the lamp housing shown in Fig. 1, the lamp I8, which in this example is a high pressure mercury vapor discharge lamp operated on direct current andv adapted to dissipate 2 /2 kw., is connected to supply-terminals I9, 20 adapted to be connected to a D. C. mains supply, for example 115 volts, in the polarity indicated, and the lamp has in series with it three resistances R1, R2, R3 and a choke L; a starter switch S5 is connected in parallel with the lamp 3. The starter switch S5 may be an electro-magnetically operated vacuum switch, and the operating coil 2! thereof may be connected in series with a control switch S2 and the contacts Q1 of a current-operated relay Q which is arranged in series with the lamp [8 so as to be operated by the current through the lamp, so that when the lamp starts the said contacts Q1 operate to open-circuit the operating coil 2| of the vacuum switch S5, whereby accidental operation of the switch S5 is prevented.

Also the operating coil 2| of the vacuum switch may be shunted by a rectifier Y and connected in series with a voltage-dropping resistance W,

' suitably the filament of an indicator lamp, for

protecting the lamp I8 against Wrong polarity of connection to the D. C. supply. A condenser Xv may be connected across the lamp I8 and the choke L, to prevent the inductive pulse produced across the choke for starting of the lamp from being fed back into the mains circuit.

The current-operated relay also operates, via the contacts Q1. which are changeover contacts, a contactor C2 which short circuits the choke L when the lamp has started; a resistance R4 shunted by contacts V1, to be referred to later, is connected in series with the contactor C2 and the mains supply, in order to reduce the current flowing through the contactor when the interlock relay is in operation, as will be explained below.

The coil of the voltage-operated relay V provided in accordance with this invention is arranged to be connected across the lamp in series with a current-limiting resistance R5 by closing of the contacts Q2 of the current-operated relay Q when the lamp starts. This voltage-operated relay V is adapted to operate only when the volta e across the lamp attains a given value, for

example volts, and it then actuates the interlock relay I via contacts V2 to enable the lamp shutters to be opened. The coil M of the interlock relay is connected across the mains supply in series with the contacts V2, which are changeover contacts, operated by the voltage-operated relay V to close the energizing circuit of the coil I 4. When a current'flows through the coil I 4 the end I! of the soft iron bar I3 abutting against the lever 8 (Figure 1 and 3) is attracted to the magnet, thus releasing the lever, which may then be manually operated to open the shutters 5 and I its operating pressure, it can be simmered, that is, run at a low current and therefore at a power dissipation considerably below its operating dissipation, as long as the shutters 5 and 6 are closed, but automatically attains its full operating dissipation when the shutters are opened. The

lamp I 6 can thus be maintained ready for immediate use while it is not required. To that end the arm of switch S1 in its open position is spring pressed against the lever 8 in the shuttersclosed position 8' of the relay (Fig. 3). As the lever is moved toward its open-shutter position 8 the arm of switch S1 is moved by the spring 2| to its closed position. Two of the resistances in series with the lamp, viz R2: and R3, thus are short circuited, so that the full operating circuit then flows through the lamp 18, which thus automatically dissipates its full power simultaneously with the opening of the shutters 5 and 6.

In operating the lamp by the arrangement described, the shutters should be closed before clos ing the mains switch S3, S4 and a conventional mechanical interlock (not shown) may be arranged to prevent the mains switch being closed if the shutters are open. During the starting period, that is, after the discharge has struck but before the operating pressure has been attained, two of the three resistances arranged in series with the lamp, viz. R1 and R2, are operative, the third, R3, being cut out by means of a contactor C1 which is automatically closed during the starting period as described below. To start the lamp, the control switch S2 for the vacuum switch S5 is closed and then opened, so closing and opening the vacuum switch. Whilst the vacuum switch S5 is closed, the inductor L as well as the resistances R1 and R2, is in series with it, and this inductor is wound with high resistance wire so as to limit to a safe value the current flowing through the switch. When the vacuum switch opens, an inductive pulse, for example of about 1000 volts, is produced across the choke L and causes the lamp to strike. The passage of current through the lamp then operates the relay Q which is in series with the lamp and causes the relay to change over the contacts Q1 and close the contacts Q2 so as to close contactor C1 shortcircuit the choke L (via Q1 and C2), open-circuit the cooperating coil of the vacuum switch (via Q1) and connect the voltage-operated relay V across the lamp (via Q2). At this stage the resistance R1 in series with the choke contactor C2 is short-circuited by means of contacts V1 subsequently to be opened by the voltage-operated. relay V.

When the lamp starts, the voltage across it is very low, for example only about 15 to 20 volts; when this voltage has risen to, say, 50 volts, the lamp is dissipating suificient power'for use, but the voltage may continue to rise and may ultimately reach a steady value of, for example, '70 to 80 volts. When the voltage attains the required value, say 50 volts, the voltage-operated-relay- V is actuated to operate the interlock relay Itorelease the shutter lever as already described and to connect an indicator G, such as a green-lamp, across the mains via V2 to indicate that the discharge lamp I8 is ready for use. The voltageoperated relay V also opens the contactor C1 (via V2) which was short circuiting the third resistance R3, so that all three resistances R1, R2, and R3 are now in series with the lamp l8, which under these conditions dissipates considerably less than its full power, for example 1 kw. Another function of the voltage-operated relay is to open the contacts V1 which were short-circuiting the resistance R4 in series with choke contactor C2.

When the lamp is required to be used, the shutters 5 and 9 are opened by manually operating the lever 8 (Figs. 1 and 3) which is now free to move, and the opening of the shutters automatically short circuits the resistances R2 and R3 as described (via S1), so that the lamp immediately dissipates its full operating power.

This application is a continuation in part of my application Serial No. 42,231, filed August 3, 1948, and owned by the General Electric Company the assignee of the present application and abandoned after the filing of this application.

While I have shown and described my invention as applied to particular systems of connections and as embodying various devices diagrammatically shown, it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination, a high pressure metal vapor discharge lamp, a circuit for operating said lamp, a housing enclosing said lamp and provided with a manually operable shutter, electromagnetic means positioned to lock said shutter in its closed position before said lamp has attained a predetermined minimum operating voltage and to unlock said shutter after said lamp has attained said voltage, and electric relay means having its coil electrically connected across said lamp so that the operation of said relay means is controlled by the operating voltage of the lamp and having a pair of contacts connected with the coil of said sateen 6 electromagnet means, said relay means being 615-- er-able to energize said electromagnet means and unlock said shutter when said lamp has attained said minimum operating voltage.

2. In combination, a high pressure metal vapor discharge lamp, a circuit for operating said lamp including series ballast resistance means, a housing enclosing said lamp and provided with a manually operable shutter, electromagnetic means positioned to lock said shutter in its closed position before said lamp has attained a predetermined minimum operating voltage and to unlock said shutter after said lamp has attained said voltage, and electric relay means having its,

coil electrically connected across said lamp so that the operation of said relay means is controlled by the operating voltage of the lamp and having a pair of contacts connected with the coil of said electromagnet means, said relay means being operable to energize said electromagnet means and unlock said shutter when said lamp has attained said minimum operating voltage, and switch means mechanically linked with said shutter so as to move to a closed circuit position on opening of said shutter and electrically connected in shunt with a portion of said ballast resistance means whereby the lamp operates at full power and brilliance on the opening of said shutter.

ANTHONY H. WILLOUGHBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,405,286 Bourne Aug. 6, 1946 2,412,292 Schneider Dec. 10, 1946 FOREIGN PATENTS Number Country Date 579,034 England July 22, 1946 579,920 England Aug. 21, 1946 

